When running on solaris sparc9 with 64 bit JDK installed I see over 70 JCK tests fail with an IncompatibleClassChange error when I use the -d64 and -Xcomp flags used together.
If either of the flags are used on their own the tests pass.
This is not a regression as it happens on 1.4.1 fcs also.

An example of one of the failing tests is:
api/java_net/DatagramSocket/index.html#Ctor

The error from this test is:

java.lang.IncompatibleClassChangeError
at javasoft.sqe.tests.api.java.net.DatagramSenderReceiver.sendReceive(DatagramSenderReceiver.java:75)
at javasoft.sqe.tests.api.java.net.DatagramSenderReceiver.sendReceive(DatagramSenderReceiver.java:42)
at javasoft.sqe.tests.api.java.net.DatagramSocket.CtorTests.DatagramSocket0003(CtorTests.java:756)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at javasoft.sqe.javatest.lib.MultiTest.invokeTestCase(MultiTest.java:397)
at javasoft.sqe.javatest.lib.MultiTest.run(MultiTest.java:193)
at javasoft.sqe.javatest.lib.MultiTest.run(MultiTest.java:125)
at javasoft.sqe.tests.api.java.net.DatagramSocket.CtorTests.main(CtorTests.java:104)
DatagramSocket0003: Failed. Test case throws exception: java.lang.IncompatibleClassChangeError